To judge from this frisky if formulaic tale, assertiveness training could prove helpful even for turtles. Tambourina Turtelli, en route to her ballet recital clad in tutu and toe shoes, reluctantly agrees to give a ride to the drum-toting Fox. Soon Moose, too, begs a lift from the ever-obliging turtle, followed by Dog, Elephant et al., each one carrying an instrument for the big event. Soon Tambourina is precariously balancing a Leaning Tower of Creatures, but finally upsets the applecart and learns to speak her mind. Several of the narrow book's spreads feature half-pages, used to depict a new character's appearance and-helped by pull-tabs-to show him playing his instrument. (The book's subtitle, in fact, is somewhat misleading: nearly all of the minimal action here is supplied by the pull-tabs.) Roffey's expressive illustrations are Technicolor bright, and a certain amusement derives from the use of larger and smaller typefaces in the repeated line, ``Tambourina wanted to say NO! But she said yes.'' Ages 3-6. (May)